1. Field of the Invention
The present invention relates to carbohydrate fermentation products which may be used in food or pharmaceutical applications and requires minimal processing steps. More specifically, the invention comprises the use of a xanthan gum broth in liquid food or pharmaceutical compositions wherein the broth medium is a carbohydrate other than whey and wherein the broth is used directly without the need for filtration and purification processing steps.
2. Technology Description
Carbohydrate fermentation products, such as xanthan gum, are commonly used as additives, such as thickening agents for food and pharmaceutical ingredients. The fermentation of carbohydrates to produce biosynthetic water-soluble gums by the action of Xanthomonas bacteria is well known. The earliest work in this field was conducted by the U.S. Department of Agriculture and is described in U.S. Pat. No. 3,000,790. Particularly well known is the action of Xanthomonas campestris NRRL B-1459 on a glucose substrate.
Xanthomonas hydrophilic colloid (i.e., xanthan gum) is produced by transferring Xanthomonas campestris bacteria to a suitable medium and conditioning it to growth through two steps before allowing it to grow in a final medium containing 3 percent glucose. After 96 hours at 30.degree. C. with suitable aeration and stirring, Xanthomonas hydrophilic colloid is produced in approximately 1% concentration. Modified fermentation processes are described in U.S. Pat. Nos. 3,391,060; 3,391,061; 3,427,226; 3,455,786; 3,565,763; and the like.
Xanthomonas hydrophilic colloid is a microbial heteropolysaccharide which contains mannose, glucose, glucuronic acid, O-acetyl radicals and acetal-linked pyruvic acid in a molar ratio of 2:2:1:1:0.5.
While Xanthomonas campestris is the bacteria of choice for the purpose of producing the biosynthetic Xanthomonas hydrophilic colloid, other Xanthomonas species may be employed such as X. begoniae, X. malvacearum, X. carotae, X. incanae, X. phaseoli, X. vesicatoria, X. papavericola, X. translucens, X. vasculorum, and X. hedrae.
In practice when xanthan gum is typically used as a thickening agent in a food or pharmaceutical composition, the fermentation broth is typically subject to processing conditions such as drying, centrifuging and the like to yield a purified powder. For example, In a typical process for clarification of a Xanthomonas fermentation broth and/or recovery of the Xanthomonas hydrocolloid component, the broth is diluted with water to reduce its viscosity, and optionally the diluted broth is centrifuged or filtered to remove suspended insoluble solids. A salt such as potassium chloride and a nonsolvent such as methanol or isopropanol are added to the broth to flocculate the gum in the, potassium form, which gum is then recovered by centrifugation or other solid/liquid separation technique. Further dissolution, reprecipitating and washing steps are usually employed. To yield xanthan gum powder, additional "downstream" processing steps such as drying, milling, sieving and packaging for customer use. There are significant costs involved in such steps and it would be desirable to omit these steps for economic reasons.
In addition, while the xanthan gum powder compositions typically are capable of thickening liquid food compositions, additional improvements in viscosity performance would be desired in homogenized foods such as salad dressings.
U.S. Pat. No. 4,299,825 suggests a process for clarifying and concentrating Xanthomonas heteropolysaccharide fermentation broth, which process includes filtration and ultrafiltration steps. The resulting clarified and concentrated material is suggested for use in foodstuffs, drugs and cosmetics, as well as a thickening agent for oil recovery operations. Despite the advances suggested in the patent, the filtration and ultrafiltration steps add significant processing costs to the manufacturer.
U.S. Pat. Nos. 4,442,128 and 4,444,792 suggests the fermentation of an organism such as Xanthomonas campestris in a dairy whey environment to yield a whey product containing a thickening polymer that serves as a thickening agent. The reference fails to suggest that other carbohydrate sources can be used as the fermentation medium.
Despite the above teachings, there still exists a need in the art for a carbohydrate fermentation product which can be produced using a minimum amount of unit processing steps and used directly in food or pharmaceutical applications.
There exists yet another need in the art for a thickening agent which demonstrates superior thickening properties in homogenized liquid foods, such as salad dressings.